Laminate Flooring on Two Different Concrete Heights

I am planning to install laminate flooring in a room the main level of a concrete slab. After peeling off the original carpet, there appears to be a few inches of uneven concrete that runs along the drywall covering the exterior walls (but not the interior walls). (Please see attached photograph.)

There is around an inch or two of blue polystyrene with a plastic moisture barrier between the "outer" concrete and "inner" concrete. The "inner" concrete appears to have been levelled (1/8-inch maximum imperfections), but approximately 1/2 inch lower than the "outer" concrete.

What should I do to raise the "inner" concrete floor to achieve a constant level throughout the room? Would I need to use levelling compound on the few inches of "outer" concrete?

Unrelated to the topic of flooring: Is the protruding "outer" concrete part of the concrete slab foundation?

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Laminate Flooring on Two Different Concrete Heights

Yes, in order to achieve a constant level you would have to level out “inner” with “outer” section.

You haven’t specified dimensions of the lower “inner” section .Having said that height difference between “inner” and “outer” section is about ˝ “ self leveling compound would be on expensive side to use. One bag 50lb bag of self leveling compound at ˝” thickness would not cover more than 10-15 sf.
For this application I would use a sand mix or rapid set with flow control ,sand mix would give you a longer working time and better workability while rapid set with a flow control would act as a self leveling compound for the half of the price + you get 9000 psi.

The” outer” section almost looks like a part of the old existing slab and new “inner’ section looks like “repair slab”. Anyhow wait for the others to reply before you get to work maybe somebody else has a better idea.
George

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Laminate Flooring on Two Different Concrete Heights

Is this a converted garage? On a garage they sometimes pour the footing first, wider than the wall, build the wall amd then pour the floor. It can be a hassle but the original builder had no plans to make it living space.

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Laminate Flooring on Two Different Concrete Heights

Sadly, it is a 2100 square feet home in expensive west-side Vancouver that cannot possibly be a converted garage... I had just bought the home at 15 years old and do not have a history of the builder. What do you mean by a "repair slab"?

The "inner" dimension is basically the entire home. But I plan to lay laminate flooring in just one room, so around 100 square feet. Would using 1/2 inch extruded polystyrene be okay to raise the "inner" level?

Laminate Flooring on Two Different Concrete Heights

Quote:

Originally Posted by mrken

Sadly, it is a 2100 square feet home in expensive west-side Vancouver that cannot possibly be a converted garage... I had just bought the home at 15 years old and do not have a history of the builder. What do you mean by a "repair slab"?

The "inner" dimension is basically the entire home. But I plan to lay laminate flooring in just one room, so around 100 square feet. Would using 1/2 inch extruded polystyrene be okay to raise the "inner" level?

Looking at the attached picture "inner" section looked newer than the "outer" section unless they have used different concrete mix...anyhow i don’t think that difference between "inner" section and "outer" section is 1/2" thought the whole room so adding 1/2 polystyrene could rise or lower some sections of the ”inner” floor ...resulting in uneven floor. In my opinion you are better of leveling the floor .